Field of the Invention
The present invention relates to a paper feed tray that is used in an image forming apparatus or the like.
Description of the Related Art
Conventionally, in image forming apparatuses such as a printer and a copying machine, a cassette-type paper feed tray is widely used. In such a paper feed tray, a side regulation plate for regulating the position of a sheet in a side direction is provided. In general, the position of the side regulation plate in the side direction can be adjusted.
As a method for fixing the position of the side regulation plate, for example, there is a method of engaging a locking member provided in the side regulation plate with a rack provided in a tray main body. By this method, the position of the side regulation plate can be adjusted with accuracy corresponding to the pitch of rack teeth. However, in this case, the paper feed tray is relatively vulnerable to shock, and for example, when the paper feed tray is swiftly fitted to an image forming apparatus main body, a tooth is skipped by its shock, and the position of the side regulation plate is displaced, with the result that the sheet is skewed.
As a method that is highly resistant to shock, there is a method of previously boring holes corresponding to a standard-sized sheet in a paper feed tray main body and utilizing the holes and another member to firmly fix the side regulation plate. However, by this method, it is impossible to firmly lock the side regulation plate in a position corresponding to an irregular-sized sheet, and the number of components is also increased, with the result that the cost is disadvantageously increased.
For example, Japanese Unexamined Patent Application Publication No. 2005-177710 proposes a method of providing a pair of engagement tooth rows in the paper feed tray main body and engaging a member on the side of the side regulation plate with these engagement tooth rows. By this method, a locking force for fixing the position of the side regulation plate is increased, and it is possible to lock the side regulation plate in a position corresponding to an irregular-sized sheet.
However, in the method of providing the pair of engagement tooth rows, in order to engage the member with both the engagement tooth rows, a high operation force such as for making phase differences coincide with each other is required. Hence, two-stage switching between cancellation and locking is needed, and in a cancellation state, the paper feed tray is more likely to be fitted because a user fails to perform a locking operation. In this case, disadvantageously, the side regulation plate is extremely easily moved.
When the locking is cancelled, and the side regulation plate is moved, a hand switching operation is needed between the operation of cancelling the locking and the operation of moving the side regulation plate. In terms of convenience, it is desirable to be able to omit such an operation.
In view of the foregoing problems, the present invention has an object to provide a paper feed tray with which it is possible to perform firm locking and it is easy to, for example, avoid a failure caused by failing to perform a locking operation.